1. Field of the Invention
The present invention relates to an information presentation apparatus and information presentation method.
2. Description of the Related Art
A technique of using a plurality of markers to calculate and obtain position/posture information of an image input apparatus has heretofore been proposed. A proposer, et al. has already proposed a system in which information included in a reference marker is read in order to obtain a general position/posture of an image acquisition section, and positions of the reference marker and a marker and/or a characteristic point disposed around the reference marker can be recognized as a “related information presentation apparatus and related information presentation method”. Here, the positions of four or more markers and/or characteristic points are recognized, and the information can be used to estimate the position/posture of the image input apparatus.
A method for obtaining the position/posture of the image input apparatus from a reference marker position is described in “High-Precision Real Time Estimating Method of Position/Posture of Rectangular Marker by Single Lens for VR Interface” (3D Image Conference '96 Proceedings pp. 167-172 Akira Takahashi, Ikuo Ishii, Hideo Makino, Makoto Chujo 1996). That is, assuming that Oc is a point of view, po is a projected image diagonal intersection, and Po is a rectangle diagonal intersection, x′ is obtained so as to minimize the following and the posture is obtained.       F    ⁡          (              x        ′            )        ·  4  ·            ·              i        ·        1              4    ⁢            (                        n          i                ⁢                  n          i          ′                    )        2  Here, a variable vector x′ is as follows.x′.(.′1.1′,.2′)
For the position, d is estimated by a least square method such that a distance between Ocpi and a vertex Pi is minimized.       d    ·                            (                                    S              0                        ⁢                          S              i                                )                ⁢                              (                                          S                i                            ⁢                              W                i                                      )                    ·                      (                                          S                0                            ⁢                              W                i                                      )                                      1        ·                              (                                          S                0                            ⁢                              S                i                                      )                    2                      ⁢  D
Subsequently, the position can be determined by an average of depth values obtained from respective vertexes.
Moreover, in “Mixed Reality” (ISBN 4-274-90283-8 Ohmsha, Ltd.) Chapter 6: Augmented Reality Tracking in Natural Feature Environments, U. Neumann, S. You, Y. Cho, J. Lee and J. Park 1999 p.101-130, a known reference point called Fiducial Mark is used to obtain the initial position of the image input apparatus. In this case, a plurality of characteristic points are extracted to obtain a projection position in an input image. The characteristic point is tracked in accordance with the movement of the input apparatus, and an optimum solution of the position of the image input apparatus is obtained.
In a conventional example, a technique is disclosed for obtaining the position/posture information of the image input apparatus, when the positions of a plurality of markers are known. However, for example, when an environment for using the apparatus extends over a broad range, it is necessary to prepare a large number of markers beforehand in the entire range for use.
When a plurality of pieces of information are to be presented at the same time, at least the markers for the presented information have to be prepared. When a sufficient space for disposing the makers can be secured, there is no problem. However, in the environment in which the installation space is limited, there is possibility that the present technique cannot be used.